Dynamic and Static Behaviors of N鈥揨鈥揘 蟽(3c鈥?e) (Z = S, Se, and Te) Interactions: Atoms-in-Molecules Dual Functional Analysis with High-Resolution X-ray Diffraction Determination of Electron Densities
文摘
The structure of 2-(2-pyridylimino)-2H-1,2,4-thiadiazolo[2,3-a]pyridine (NSN) indicates that the molecule has a planar geometry with a linear N路路路S路路路N linkage, creating a tetracyclic structure of the formal C2v symmetry. To clarify the nature of the NSN 蟽(3c鈥?e) bonding, together with the related NSeN and NTeN, the dynamic and static behaviors are investigated by applying atoms-in-molecules (AIM) dual functional analysis to both the fully optimized and perturbed structures. The structures were optimized computationally, retaining C2v symmetry. All bond critical points are detected as expected and exhibited on both sides of the N路路路Z路路路N moiety which supports the formation of NZN 蟽(3c鈥?e). It is confirmed that N路路路S路路路N is of the covalent nature close to Me2S+--Cl or Me2Se+--Br, whereas N路路路Se路路路N and N路路路Te路路路N have the (regular) CS nature close to the CT adducts of Me2S(--Cl)2 (TBP) and Me2Se--Br2 (MC), respectively. An experimental high-resolution charge density determination has been performed on NSN, which thoroughly supports the theoretical results. Very similar results are obtained in the analogous pyrimidyl derivatives for N路路路S路路路N, N路路路Se路路路N, and N路路路Te路路路N. AIM dual functional analysis, as validated by experimental high-resolution charge densities, is thus confirmed to be an excellent method to elucidate the nature of these interactions.